The present disclosure relates generally to communication systems, and more particularly, to an uplink control resource allocation methods and apparatuses in a wireless communications system.
Wireless communications systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communications systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power). Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.
These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example of an emerging telecommunication standard is Long Term Evolution (LTE). LTE is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by Third Generation Partnership Project (3GPP). It is designed to better support mobile broadband Internet access by improving spectral efficiency, lower costs, improve services, make use of new spectrum, and better integrate with other open standards using OFDMA on the downlink (DL), SC-FDMA on the uplink (UL), and multiple-input multiple-output (MIMO) antenna technology. However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in LTE technology. Preferably, these improvements should be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.
In wireless communications systems employing legacy LTE, a plurality of UEs served by a particular network entity (e.g., eNodeB) may receive control information from the eNodeB over a shared Physical Downlink Control Channel (PDCCH). The control information included in the PDCCH may include one or more uplink resource grants for UE transmission of uplink data in a future LTE uplink transmission window. When control information is to be transmitted by the UE in the uplink, however, it is often inefficient for the network entity to transmit dynamic grants for each uplink control information transmission. Furthermore, pre-allocating fixed resources (in time and frequency) without knowing a dynamic uplink transmission window length likewise leads to system inefficiencies.
As such, improvements in the uplink control resource allocation are needed to mitigate these present inefficiencies.